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Oceans 11 – Ms. Bowie
Coral Reefs
Page 1 of 16
Coral Reef Facts Reading
http://coral.org/
What is a coral reef?
Coral reefs are one of the most biologically diverse
ecosystems on earth, rivaled only by tropical rain forests.
They are made up not only of hard and soft corals, but also
sponges, crustaceans, mollusks, fish, sea turtles, sharks,
dolphins and much more.
Competition for resources such as food, space and sunlight are some of the primary
factors in determining the abundances and diversity of organisms on a reef. Each
component of a coral reef is dependent upon and interconnected with countless other
plants, animals and organisms. This means that changes in the amount of one species
can drastically alter both the diversity and abundances of others. While natural causes
such as hurricanes and other large storm events can be the cause of such changes, it is
more commonly human actions that affect these types of shifts in the ecosystem.
For example, overfishing of herbivorous (plant eating) fish often results in increased
growth of algae and sea grasses. This generally results in an increase in other
herbivorous marine life, such as sea urchins. Over time all ecosystems will naturally
establish these types of balances between predators and prey and organisms in
competition for similar resources. The question is how long those balances take to
establish and what other reef relationships they affect.
One of the seven natural wonders of the world— the Great
Barrier Reef. This is a portion of the Great Barrier Reef seen
from space. The reef is over 130,000 square miles and stretches
for approximately 1,600 miles along the northweast coast of
Australia.
Of course, the Great Barrier Reef is not the only coral reef on Earth. These living,
growing, changing structures thrive in waters within a 30-degree band north and south
of the Equator. But you won’t find them just anywhere within this band. Coral polyps
are very “particular” about their environment:
 The water must be shallow.
 The weather must be sunny.
 There must be very few nutrients in the vicinity.
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Coral Reefs
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Water with few nutrients? It seems to make no sense…. Every science book tells you
that animals don’t produce their own food; they get food from their environment. So
how can an animal thrive in an environment that’s poor in nutrients?
What is Coral?
Corals are sometimes called “living rocks”. That is because
the hard, rocky structures we often think of as “corals” are
actually just the hard skeletons of tiny animals, known as
coral polyps.
Coral polyps are soft bodied animals that release chemicals
that form the hard, calcium carbonate structures that can form underwater ridges and
mounts. Polyps range in size from a pinhead to a foot in length.
Coral polyps have a very particular way of thriving. The “very particular way” has to do
with symbiosis. Symbiosis is an interdependence, or close association, between two
organisms. In a symbiotic relationship, both organisms benefit.
Coral polyps have a symbiotic relationship with tiny plant-like organisms, an algae,
called zooxanthellae (ZOH-uh-zan-THEL-ee).
Each polyp lives in a symbiotic relationship with a host zooxanthellae that gives the
coral its color. Zooxanthellae take in carbon dioxide, process it through photosynthesis,
and give off oxygen and other important nutrients that are then used by the host polyp.
As in all photosynthesizing organisms, this means that corals must be exposed to lots of
sunlight. This means that corals are usually only found in shallow waters that are clean
and clear.
There are two kinds of corals: hard and soft. Hard corals (Scleractinia), such as brain,
star, staghorn, elkhorn and pillar corals have rigid exoskeletons, or corallites, that
protect their soft delicate bodies. Soft corals (Gorgonians), such as sea fans, sea whips,
and sea rods, sway with the currents and lack an exoskeleton.
Oceans 11 – Ms. Bowie
Coral Reefs
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Types of Coral Reefs:
Scientists generally divide coral reefs into four classes: fringing reefs, barrier reefs,
atolls, and patch reefs.
Fringing reefs grow near the coastline around islands and
continents. They are separated from the shore by narrow,
shallow lagoons. Fringing reefs are the most common type of
reef that we see.
Barrier reefs also parallel the coastline but are separated by
deeper, wider lagoons. At their shallowest point they can
reach the water’s surface forming a “barrier” to navigation.
The Great Barrier Reef in Australia is the largest and most
famous barrier reef in the world.
Barrier reefs are extensive linear reef complexes that parallel
a shore, and are separated from it by lagoon.
Atolls are rings of coral that create protected lagoons and are
usually located in the middle of the sea. Atolls usually form
when islands surrounded by fringing reefs sink into the sea or
the sea level rises around them (these islands are often the
tops of underwater volcanoes). The fringing reefs continue to
grow and eventually form circles with lagoons inside.
Patch reefs are small, isolated reefs that grow up
from the open bottom of the island platform or
continental shelf. They usually occur between
fringing reefs and barrier reefs. They vary greatly in
size, and they rarely reach the surface of the water.
The term "patch reef" is commonly used to refer to
comparatively small, isolated outcrops of coral surrounded by sand and/or seagrass
Oceans 11 – Ms. Bowie
Coral Reefs
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Biodiversity
Whether an atoll, a barrier reef, or a
fringing reef, these structures are home
to a huge number of creatures: seabirds,
sponges, jellyfish, starfish, shrimp, rays,
snails, crabs, lobsters, sea turtles, and
sea snakes, to name just a few.
Coral reefs represent less than 1 percent
of the ocean floor, but are home to almost one-quarter of all marine animals.
According to the National Ocean Service, reefs may be habitats for millions of
species that haven’t even been identified yet!
What is the coral reef ecosystem?
The health, abundance and diversity of the organisms that make up a coral reef is
directly linked to the surrounding land and marine environments. Mangrove forests and
seagrass beds are two of the most important facets of the greater coral reef ecosystem.
Mangroves are salt-tolerant trees that grow along tropical and
sub-tropical coasts. Their complex root systems help stabilize the
shore line, while filtering pollutants and producing nutrients.
Their submerged roots and detritus provide nursery, breeding,
and feeding grounds for invertebrates, fish, birds, and other
marine life. Many of the animals raised in mangroves migrate to
coral reefs for food, spawning and habitat.
Seagrasses are flowering plants that often form meadows
between mangrove habitats and coral reefs. They form the
foundation of many food webs, providing nutrients for
everything from sea urchins and snails to sea turtles and
manatees. Seagrass also provides protection and shelter for
commercially valuable species such as stone crabs, snappers
and lobsters. Additionally, they filter the water column, prevent seabed erosion, and
release oxygen essential for most marine life. The ecosystem services of mangroves and
seagrass meadows are vital to the long term health of coral reefs.
Oceans 11 – Ms. Bowie
Coral Reefs
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There is another very important element of the reef ecosystem that
is often over looked: the land. Pollutants, nutrients and litter enter
near shore waters through rivers, streams, underground seepage,
waste water and storm water runnoff. Even areas hundreds of miles
from the coast can effect the clarity and quality of water flowing to
the reef. It does not matter how far removed a pollutant may seem,
it all flows down stream and it can all impact our marine
environment and our reefs.
The Importance of Coral Reefs
Any diver can tell you that coral reefs are beautiful. They are like undersea cities, filled
with colorful fish, intricate formations and wondrous sea creatures. The importance of
coral reefs, however, extends far beyond the pleasure it brings to those who explore it.
Coral reefs play an essential role in everything from water filtration and fish
reproduction to shore line protection and erosion prevention.
A Barrier from Storms and Surge
Reefs play an important role in protecting the shoreline from
storms and surge water. Barrier reefs, such as Florida’s, were
named for the way they reduce waves and buffer the shores.
Barrier reefs help stabilize mangroves and seagrass beds,
which can easily be uprooted by large waves and h6 currents.
Erosion prevention is particularly important in coastal areas
such as the Florida Keys, where much of the shore is lined
with residential homes and commercial buildings.
Coral reefs help protect neighboring shorelines from the effects of extreme wave action.
They also protect coastal wetlands and prevent
erosion.
Water Filtration
Most corals and sponges are filter feeders, which
means that they consume particulate matter
suspended in the water column. This contributes to
enhanced quality and clarity of our near shore
waters.
Oceans 11 – Ms. Bowie
Coral Reefs
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One fish, two fish
As the foundation for complex food webs, coral reefs support an
incredible diversity of fish. Algae, soft coral, sponges and
invertebrates create the base of this web. From small herbivorous
fish to large predatory fish, all find food and protection on the reef.
Along side reef fish is an equally diverse array of marine crustaceans, reptiles and
mammals. Everything from lobsters and octopus to sea turtles and dolphins depend on
the reef for food, habitat and protection. Each animal plays an important role in the reef
ecosystem, be it filtering water, consuming prolific algae or keeping a particular species
under control. By supporting such a wide range of plants and animals, reefs are able to
maintain balanced relationships between predators and prey and organisms in
competition for the same resources. It is these balanced relationships that keep our
marine ecosystems diverse and abundant with life.
Nutrition & Health
Fish and other marine life have been a primary source of protein for as
long as people have lived along the coast. From small scale artisanal
fisheries to major commercial fleets, harvesting of marine life is a major
economic force in all of the world’s oceans. Local fisheries, such as
lobster, stone crab, snapper and grouper, all directly rely on the reef for spawning and
habitat. Other fisheries, such as tuna, dolphin and other pelagic species, rely on the reef
indirectly, though the bait fish that they consume.
As you read this article, research is taking place to develop medicines from the plants
and animals of the reef. A few have already been developed, including drugs that fight
several forms of cancer.
Economic Development
Coral reefs often form the backbone of local economies. Tourists coming
to dive need not only dive boats and guides, but also restaurants, hotels
and commercial and entertainment facilities. In many cases, tourism associated with
reefs has expanded to transform the entire economy of a region. This of course has
both positive and negative consequences for both the marine environment and the
communities involved. For example, someone who harvests sea turtle eggs may choose
to sell turtle tours as an alternative livelihood. On the other hand, an unmonitored
number of tourists may result in environmental problems such as coral damage,
pollution and inadequate waste treatment.
Oceans 11 – Ms. Bowie
Coral Reefs
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Reefs Under Attack
Despite their importance, coral reefs are under threat. Overfishing, industrial runoff,
sewage, agricultural waste, and erosion due to land clearing all pose dangers to these
sensitive ecosystems. Damaging fishing techniques, such as blast fishing, which uses
powerful explosives to startle fish out of hiding, are another hazard.
Marine Protected Areas, or MPAs, have become important in protecting and managing
coral reefs and their inhabitants. In addition, marine
parks, such as the Great Barrier Reef Marine Park,
have been established expressly to protect reefs.
Efforts are also underway to restore damaged reefs
through coral farming — growing polyps in nurseries
and then planting them on an existing reef.
In addition, there are now artificial surfaces to
promote the growth of new reefs. Called reef balls,
these hollow spheres are made of concrete specially
designed to attract coral and other marine
organisms. Today, over 50,000 reef balls are in place
around the world.
Rising sea temperatures and coral bleaching
Coral reefs can live only within a
certain temperature and salinity
range. Global warming caused by the
green house effect has raised the
temperature of the oceans so high
that the coral get sick and die. Even a
rise of one degree in the average
water temperature can hurt the
coral. Due to global warming, 1998 was the hottest year in the last six centuries and
1998 was the worst year for coral.
Coral bleaching, induced by high water temperatures, has raised concerns about these
fragile ecosystems. Coral bleaching occurs as coral tissue expels zooxanthellae, a type
of algae that resides in the structure of the coral, and is essential to the coral's survival.
Oceans 11 – Ms. Bowie
Coral Reefs
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The term bleaching is used because the dazzling colors of living corals are due to the
colors of zooxanthellae in coral tissue, and when zooxanthellae are lost, corals appear
white, or “bleached.”
Coral bleaching is not well understood by scientists. Many different hypotheses exist as
to the cause behind coral bleaching, but the strongest evidence points to unusually
warm sea surface temperatures as being the main factor (Glynn 1993). Coral bleaching
events worldwide have been attributed to sea surface temperatures (SSTs) rising and
staying as little as 1°C higher than the usual average monthly maximum SST during the
hottest months of the year (Goreau and Hayes 1994).
In Jamaica, significant coral bleaching and death occur when SSTs remain at 29.3°C or
higher for one month (Hoegh-Guldberg 1999). Therefore, in the Caribbean and Florida
Keys, when SSTs rise and stay above this thermal threshold, coral bleaching is likely to
occur. Mass coral bleaching was first recognized on the Pacific coast of Panama
following the 1982-83 El Nino events (Glynn 1984). The warm SSTs associated with the
El Nino event were identified as the cause of death of over 99% of corals and the
complete loss of reef structures in the Galapagos Islands and the death of over 50% of
corals in Panama (Glynn and D’Croz 1990; Glynn 1993). The sensitivity of corals to small
temperature changes then became a major concern of researchers as predictions of
global warming and stronger, farther-reaching El Nino events came to light. SSTs are
expected to continue to increase worldwide (Hoegh-Guldberg 1999) and El Nino events
are expected to increase in frequency, strength and duration, endangering the future
survival of coral reefs.
Other causes of coral bleaching
Apart from heat stress, other causes of coral bleaching may include:
 increased exposure to ultraviolet (UV) radiation; large amounts of storm water
from heavy rains flooding the reef;
 the exposure of coral to certain chemicals or diseases; sediments such as sand or
dirt covering the coral; excess nutrients such as ammonia and nitrate from
fertilizers and household products entering the reef ecosystem. Often coral reefs
are exposed to a combination of these factors.
Oceans 11 – Ms. Bowie
Coral Reefs
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Coral reefs are suffering the hardships of environmental Average global sea
temperature has been rising gradually over several decades, which is generally believed
among the scientific community to be due to global warming. Coral bleaching is being
widely documented. Coral bleaching occurs when the microscopic plants, or
zooxanthellae, which live in coral tissue, stop functioning. The zooxanthellae provide
corals with color, food and most of their ability to rapidly grow skeletons. Without
them, corals can die.
Look at the threats to each reef. How many of those are human threats? How many are
natural threats? Many potential threats exist, including destructive fishing, anchor
damage, pollution, sedimentation, bleaching, diseases, storms, and biological
outbreaks. Although bleaching may be argued to be a result of human threats to the
reef, these events are classified under natural threats since, more often than not, the
incidents reported in the literature attribute bleaching to a natural cause.
The most obvious sign that coral is sick is coral bleaching. That is when either the algae
inside die or the algae leave the coral. The algae are what give coral its color, so without
the algae the coral has no color and the white of the limestone shell shines through the
transparent coral bodies. It has been shown that stress caused by pollution, solar
radiation, changing salinity, and bacteria can also result in coral bleaching.
Rate of coral bleaching
Coral bleaching is a natural process. For thousands of years, fishermen have noticed
mysterious whitening of the reefs. What is not natural is the rate at which coral
bleaching is occurring. In 1998, the worst coral bleaching in 700 years struck the Great
Barrier Reef, followed by an even worse bleaching only 4 years later. Massive areas of
corals were affected all over the world. In Australia alone, the 2002 bleaching saw
nearly 60 per cent of the reef suffer bleaching and, in the worst areas, 90 per cent of the
coral was bleached.
Corals which had thrived for hundreds of years suddenly died in 1998. It was the worst
year ever recorded globally for coral bleaching, and it brought the hottest sea surface
temperatures since 1982.
In 1998 coral reefs around the world experienced the most extensive and severe
bleaching in recorded history. Coral bleaching was reported in 60 countries and island
nations at sites in the Pacific Ocean, Indian Ocean, Red Sea, Persian Gulf, Mediterranean
Oceans 11 – Ms. Bowie
Coral Reefs
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and Caribbean. Indian Ocean corals were particularly severely impacted, with greater
than 70 percent mortality reported in the Maldives, Andamans, Lakshadweep Islands,
and in Seychelles Marine Park System. The 1998 mass bleaching was coincident with
anomalously high sea surface temperatures. That year was the warmest of this century
(NOAA, 1999), and tropical sea surface temperatures were the highest in the modern
record (Strong et al., 1998). For many parts of the Pacific, the 1997-98 mass bleaching
has been linked to the strong El Niño-induced seawater warming.
Can corals survive bleaching?
In the past, rapid changes of climate have sometimes led to extinctions. The dinosaurs
were wiped out 65 million years ago, and there have been several mass extinctions
before and since. Does the coral have any hope? If a channel of cold water constantly
runs through the warm water, thus keeping the zooxanthellae cool, then those corals
can survive. Another way in which corals can survive is just by being tougher than
others, in the same way that some people are always healthy while other people are
always sick.
Protecting coral reefs
Perhaps the best thing we can do is to protect the corals that do survive bleaching
better than others. One way we can do this is by creating marine parks: areas protected
in some way from souvenir hunters and activities such as fishing and boating. At the
moment less than 5 per cent of the Great Barrier Reef is protected from fishing. The
Great Barrier Reef Marine Park Authority (GBRMPA) wants to increase this area to 25
per cent. An important consideration is to locate marine parks in areas where the coral
is resistant to bleaching. If the coral dies, eventually the fish and other marine species
will die too. The other thing we can do for the reef is to keep an eye on it. The reef has
2.4 million visitors every year, and these people go to places scientists can’t always get
to. GBRMPA can use information from visitors about where they saw bleaching. And,
just as importantly, where they didn’t see bleaching. This helps scientists to form an
overall picture of which areas are vulnerable to bleaching. Though the reefs may not be
doomed, there is definitely cause for concern. Some scientists have predicted that by
2030 massive and devastating coral bleaching events will occur every year. Other
scientists believe that there is a future for the reefs and that though the reefs may
change; they will be there in some form or another. We can only hope that they are
right.
Oceans 11 – Ms. Bowie
Coral Reefs
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Coral Reef Reading Comprehension Questions
Name: _____________________________________
1)
Section: _____ Date: December 9th, 2016
Give a definition of biodiversity: ___________________________________________________
______________________________________________________________________________
2)
Which land biome / ecosystem is most similar to the coral reef with respect to biodiversity?
3)
List 10 animals you would expect to find on the coral reef:
4)
Why is any change caused to one species on the coral reef such a problem for all the other
organisms on the reef?
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
5)
Name ONE of the NATURAL wonders of the world: ____________________________________
6)
What is the area/range on the planet where tropical coral reefs can be found? ______________
______________________________________________________________________________
7)
List 3 conditions that must exist in order for coral polyps to grow:
1
2
3
Oceans 11 – Ms. Bowie
8)
Coral Reefs
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Of the 3 conditions you listed in the previous question, which one seems odd to you? Why?
______________________________________________________________________________
______________________________________________________________________________
9)
What part of "coral" is alive? ______________________________________________________
______________________________________________________________________________
10)
Describe the term "Symbiosis": ____________________________________________________
______________________________________________________________________________
11)
What symbiotic relationship exists within coral? ______________________________________
______________________________________________________________________________
12)
What are zooxanthellae? Where do they live? ________________________________________
______________________________________________________________________________
13)
Describe 3 things do zooxanthellae give to the corals:
1
2
3
14)
How does the job of zooxanthellae explain why corals are found in nutrient-poor waters?
______________________________________________________________________________
_____________________________________________________________________________
Oceans 11 – Ms. Bowie
15)
Coral Reefs
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The are two main categories of corals Hard corals and soft corals. Give at least 3 examples of
each:
Hard corals
Soft corals
16)
There are 3 main types of coral reefs: fringing barrier and atolls. Describe each
Fringing Reefs
Barrier Reefs
Atolls
17)
Patch reefs are not technically a category of reef. Describe what is meant by the term Patch
Reef?
______________________________________________________________________________
_____________________________________________________________________________
Oceans 11 – Ms. Bowie
18)
Coral Reefs
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What are mangrove forests? _____________________________________________________
_____________________________________________________________________________
19)
How are mangrove forests helpful? Give at least 4 ways:
1
2
3
4
20)
How are mangrove forests important to coral reefs? ___________________________________
______________________________________________________________________________
21)
What are seagrass meadows? Where do they usually grow? ____________________________
______________________________________________________________________________
22)
List 4 animals that often feed on the seagrasses:
23)
Which organisms that humans like to eat (therefore have economic value) often find shelter in
the seagrasses?
24)
List 3 important jobs the seagrasses carryout which helps nearby coral reefs?
1
2
3
Oceans 11 – Ms. Bowie
25)
Coral Reefs
List 5 ways that pollutants, nutrients & litter can make it from land source to the coral reefs:
1
2
3
4
5
26)
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Explain the importance of coral reefs with respect to each of the following:
Barrier from storms &
surges
Coastal erosion
Water filtration
Biodiversity
Nutrition for humans
Health &
Pharmaceuticals
Economy $$$
Oceans 11 – Ms. Bowie
27)
Coral Reefs
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List 5 threats to delicate coral reef ecosystems:
1
2
3
4
5
28)
Describe 4 ways people are trying to protect the delicate coral reef ecosystems:
1
2
3
4
29)
What is coral bleaching? _________________________________________________________
______________________________________________________________________________
30)
List at least 6 factors that can lead to coral bleaching: